The 4th Air Defense Artillery Regiment was constituted 1 June 1821 in the Regular Army as the 4th Regiment of Artillery and organized from new and existing units with Headquarters at Pensacola, Florida. As a result of the division of the Artillery Corps into the Coast and Field Artillery Corps, the Regiment was broken up 13 February 1901, and its elements reorganized and redesignated as separate numbered companies and batteries of the Artillery Corps.